The present invention relates to arrangements in lifting devices, and particularly to an arrangement which provides an improvement of the operational capacity of a so-called spreader, designed for lifting a goods-container.
For the purpose of loading and re-loading in container transport, various types of lifting devices exist, for example, the type from which a rails-bound or wheel-supported crane is lowered over a container to engage with its corner fittings during a lift from a vessel to a dock, for example. The present invention is aimed at improving the operational capacity of such lifting devices, commonly referred to as spreaders. The following disclosure relates to a design comprising a central housing body in which two or several beams are accommodated for telescoping and oppositely directed relative movements. The beams have at their outer ends a pair of coupling means for engaging with the corner fittings, and are driven hydraulically or electrically to extend or retract, respectively, to adapt to the container""s length. The driving means and the movement-transmitting means are arranged in or on the housing body, which is suspended by the cables of the crane or positioned at the end of the beam of the crane.
The handling of containers is a constantly developing activity, and continuous adaptation of current technique is required to fill the needs of the transport market. In the technical field there are containers of various standardised lengths of 20, 30, 40 and 45 feet. Because of the demands for rational and cost-saving goods handling, a growing need has arisen to handle containers also of greater lengths, for example 48, 53 feet, etc. in docks and goods terminals. Thus, there is a need for spreaders which have great flexibility and a capacity to handle containers of greater lengths so as to avoid set up time for changing lifting arrangements.
The technical solutions to accommodate the above mentioned requirements are limited, among other things since the length of the center housing body shall permit retraction also to allow the containers, having the shortest lengths, to be lifted. Other restrictions reside in the total weight of the spreader and the position of a coupling member at the outer end of the spreader beam. These limitations cause problems when designing an arrangement wherein the opposite ends of the beams are moved to pass each other or to overlap in the retracted end position of the beams. One previous solution to these problems comprises hydraulic, telescopic beams of conventional type in two or more sections.
The present invention is aimed at providing an alternative, cost-saving solution to the above stated problems by providing a spreader, comprising a central housing, wherein at least two beams are stored in parallel and which project and retract in opposite directions, respectively. Said spreader, on each respective beam, has an axially moveable, additional beam member, acting as an extension of the beam when the beam is projected, and when the beam is in retracted position is designed to rest in an overlapping position on the beam.